Rotary seen printing machine with improved mounting for the screen

ABSTRACT

There is disclosed an improved rotary screen printing machine of the type wherein the printing stations are each equipped with a circular printing screen which, as required, can be removed and again remounted. According to an important aspect of the invention, the circular printing screen is secured through the agency of a resiliently biased intermediate member to the mounting or support disk means arranged at the machine frame.

United States Patent inventors Kurt Feier Riedholz; Hans Werthmuller, Wi1er; Max Breitenmoser, Wiler near Utzenstorf, all of, Switzerland Appl. No. 761,526 Filed Sept. 23, 1968 Patented Aug. 17, 1971 Assignee Firma Fritz Buser AG Wiler near Utzenstorf, Switzerland Priority Sept. 26, 1967 Switzerland 13406/67 ROTARY SEEN PRINTING MACHINE WITH IMPROVED MOUNTING FOR THE SCREEN 8 Claims, 5 Drawing Figs.

U.S.C1 101/116, 101/127.1 Int. Cl .t 1141i 15/38, B411 13/06 Field ofSearch 101/119,

[56] References Cited UNITED STATES PATENTS 198,508 12/1877 Dowling 287/129 2,453,383 11/1948 Rathman.. 64/15 (C) 2,803,474 8/1957 Wilson 287/129 3,151,551 10/1964 Dutroeta1.... 101/216 3,164,083 I/l965 Irvine 101/216 X 3,205,814 9/1965 Huck 101/216 3,214,942 11/1965 I-Iill 287/130X 3,422,755 1/1969 Murakami 101/119 FOREIGN PATENTS 505,102 8/1954 Canada 287/130 918,867 2/1963 Great Britain 287/130 Primary Examiner-J. Reed Fisher Att'orneyWerner W. Kleeman ABSTRACT: There is disclosed an improved rotary screen printing machine of the type wherein the printing stations are each equipped with a circular printing screen which, as required, can be removed and again remounted. According to an important aspect of the invention, the circular printing screen is secured through the agency of a resiliently biased intermediate member to the mounting or support disk means arranged at the machine frame.

PATENTYED mm 7 I97! 3. 599 .565

SHEET 1 [IF 2 ATTORNEYS ROTARY SEEN PRINTING MACHINE IMPROVED MOUNTING FOR THE SCREEN BACKGROUND OF THE INVENTION The present invention broadly relates to an improved rotary screen printing machine and, in its more specific aspect, concerns an improved mounting and attachment device'for the circular printing screen.

Printing machines of the aforementioned type are equipped with a number of printing stations, each of which incorporates a respective circular printing screen which rotates in synchronism-with the backing cloth or printers blanket upon which is situated the material or fabric to be printed. Furthermore, beneath each circular printing screen below the printers blanket there is arranged a counterpressure roller which supports the printers blanket.

It is of extreme importance for the proper functioning of the rotary screen printing machine that the circular printing screens can be easily exchanged at any time. Additionally, the centering of the circular printing screen must be as accurate as possible. The circular printing screens are formed of very thin material having a thickness of only several hundreths of a millemeter. At the edges of these cylindrical-shaped circular printing screens there are arranged flanges by means of which the screens can be centered. The exact attachment of these flanges is difficult, and therefore,v possible inaccuracies of these flanges have to be taken up or compensated for by the attachment device for the circular screens.

The prior art attachment devices for circular screens of the type under consideration are not in the position of satisfying all of these requirements.

According to a known physical construction of attachment device for circular printing screens there is utilized a so-called bayonet connection. In such construction the attachmentring, for instance, is provided with a number of retaining cams or holding dogs, for instance, for such cams or dogs, whereas the counter member, that is to say the-circular printing screen possesses a corresponding number of shoulders or collars which come to bear beneath the retaining or holding cams of the attachment ring. In order to secure the circular printing screen it is necessary to initially enlarge the spacing of both intermediate members until the circular printing screen is introduced between both of the intermediate rings and is brought into alignment with such. The thus introduced screen must be manually retained in this aligned position until the intermediate ring is inwardly displaced-such that the cams and the shoulders are disposed in the mutually correct position. Onlythen is it possible to lock into place the circular printing screen by rotating the attachment ring. The same cumbersome operations, however, in the reverse sequence, are also necessary during dismantling of the screen. The only advantage, at best, which can be attributed to this arrangement is that the screen can be dismantled in every position, that is to say, in every angle of rotation with regard to the design or pattern which is to be printed.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to provide an improved mounting and attachment device for circular printing screens in which the drawbacks of the prior art'constructions can be effectively prevented and which i I Now, in order to implement these and still further objects of 'the inventiomwhich will become more readily apparent as the description proceeds, the invention contemplates'attaching the circular printing screenthrough the agency of a resiliently biased intermediate member to a support or mounting disk means arranged at the machine frame. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood, and objects other than those set forth above will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 is a fragmentary sectional view through a first embodiment of mounting device for the circular printing screens of a rotary printing machine;

FIG. 2 is a front view of the mounting device employed in the arrangement of FIG. 1;

FIG. 3 is a fragmentary sectional view of a further embodiment of mounting and centering device for circular printing screens at an intermediate member;

FIG. 4 is a front view of the intermediate ring equipped with the retaining hooks or cams of the mounting or support device of the arrangement of FIG. 3; and

FIG. 5 shows details of the locking means for the retaining cams or hooks used in the arrangement depicted in FIGS. 3 and 4. DESCRIPTION OF THE PREFERRED EMBODI- MENTS I Referring now to the drawings, it should be understood that reference numeral 1 designates a circular printing screen which is formed of a fine perforated material. Flanges 2 are secured to the ends of the circular printing screen 1. Generally, these flanges 2 are adhesively bonded by means of their associated cylindrical portion 2' in the associated circu-' lar printing screen. In so doing, it is quite difficult to position or maintain the flange 2 exactly perpendicular to theaxis of the circular printing screen.

In the exemplary embodiment of inventive rotary printing machine, a respective support or bearing plate 3 is rotatably mounted at each end of the circular printing screen 1 at the schematically depicted machine frame 50. In order to preserve clarity in illustration and to simplify the schematic representation, only one end of the circular printing screen 1 has been shown and will be considered in detail. Furthermore, it should be seen that a resiliently biased or loaded plate or disk member 4 is mounted at the associated support or bearing plate 3. This plate or disk member 4 is centered by means of entrainment bolt means 5 which are fixedly anchored in the support or bearing plate 3 and during rotation of the support or bearing plate 3 the plate or disk 4 is rotatably entrained. Each of the bolt means 5 carry a pressure or compression spring 6 which, on the one hand, bears against the associated bolthead 5 and, on the other hand, bears at the bottom or base 7 of the corresponding bore 7 provided at the plate or disk 4, so that the latter is pressed or urged toward the bearing plate 3. -One of both bearing plates 3 is constructed to be displaceable so that the circular printing screen 1 can be tensioned' and relieved of tension, as desired. By carrying out a more-or-less pronounced compression of the springs 6 by appropriately axially moving or shifting the displaceable bearing plate 3 it is possible to regulate and vary the tension force at the circular printing screen i.

During tensioning of the circular printing screen 1 an intermediate space exists between the support or bearing plate 3 and the-intermediate disk 4. Now, it a circular printing screen 1 is inserted wherein the flange 2 is not located exactly perpendicular or vertical to the axis of the circular printing screen, then this screen will tend to move with a wobbly motion during rotation. This wobbly motion is also carried out by the intermediate plate or disk 4 at which the flange 2 is fixedly coupled. However, due to the gap or space existing between the support or bearing plate 3 and the disk or plate 4, this wobbly movement is not transmitted further. Consequently, the inaccuracies in the position of the flange 2 are compensated.

In order to permit a rapid mounting and dismantling of the circular printing screen 1, two stationary hook members 8 as well as a movable locking hook or lever 9 are mounted at the resiliently loaded or biased intermediate disk member 4. The movable hook member 9 is equipped with a locking device which is constructed such that the movable hook member 9 exactly centers the flange 2. Further, it will be seen that the locking device 10 is pivotably mounted at 10 to the movable hook member 9 and engages beneath a shoulder 4' provided at the intermediate disk or plate 4. As shown in FIGS. 1 and 2, the positioning and entrainment of the circular printing screen 1 with respect to the disk or plate 4 is aided by means of a pin 25 secured to plate 4 and adapted to extend through a bore 26 in the flange member 2.

The mounting or dismantling of a circular printing screen 1 is undertaken in the following way: the bearing disks 3 are rotated until the movable hook member 9 is located in its uppermost position. By applying a pressure inthe direction of the arrow 51 to the locking device 10, it is possible to open the movable hook member 9, whereupon the screen 1 can be lifted out. Previously, it is of course necessary to relieve the screen 1 from the tension force acting upon such. Additionally, it might be mentioned that, if desired, the locking lever 10 can be equipped with a resilient member, such as a spring 52 for instance, which tends to rotatably urge such into its locking position. Hence, during the locking of the screen 1, the movable hook member 9 is therefore automatically locked. In order to entrain the circular printing screen 1 it is possible to provide special means, for instance, in the form of entrainment bolt means.

In FIGS. 3 to 5, inclusive, there is shown, a further embodiment of inventive mounting and centering device for circular printing screens. Once again, reference numeral 1 designates the circular printing screen and reference character 2a generally denotes the flange means which incorporate an end flange 2b and a cylindrical portion 3a, the latter of which serving to adhesively bond flange means 20 in the associated circular printing screen 1. Possible deviations of the position of the flange means 20 from a vertical plane with regard to the longitudinal axis of the associated circular printing screen 1 are compensated, just as in the embodiment of FIGS. 1 and 2, by means of the intermediate members 4:: arranged at both sides of and at the ends of the circular printing screen 1. The depicted intermediate member 4a is supported together with other components, for instance a driving gear 18, at a support 24 carried by the machine frame. The intermediate members 4a and the components assembled together therewith can possess centrally arranged opening means 4b, which, for instance, can be employed for inserting the nonillustrated squeegee system.

Continuing, it will be observed that each intermediate member 4a is centered by means of the entrainment bolt means 5a which are. mounted to be lengthwise displaceable in the associated support or bearing plate 8a, and such intermediate member 4a' is rotatably entrained during rotation of the driving gear 18 operably connected with the support or bearing plate 8a. Furthermore, it should be understood that the bolt means 5a carry a pressure or compression spring 6a which, on the one hand, just as in the previous embodiment, bears against'the associated bolthead 5' and, on the other hand, also is supported at the base of floor 7' of the associated bore means 7a located at the support or bearing plate 8a. Consequently, the intermediate member 4a is urged or pressed toward the bearing plate 8a. One of both bearing plates 8a is mounted to be displaceable, so that the circular printing screen 1 can be advantageously tensioned or relieved of tension. Thus, by carrying out a more-or-less pronounced compression of the spring means 6a, it is possible to vary the tension force at the circular printing screen 1.

Now, for the purpose of rapidly inserting and removing or dismantling the circular printing screen 1, a number of retaining cams or hooks 9 a are arranged at the resiliently mounted intermediate member 4a. As best observed by referring to FIG. 3, the retaining cams 9 a possess a substantially U-shaped profile, at one leg 9' of which there connects a web portion 90. The retaining or holding cams 9a are situated together with their web portion and their therewith connected leg portion 9' in a groove 10a which extends about the entire periphery or circumference of the associated intermediate member 4a. For the purpose of mounting and dismantling the retaining or holding cams 9a, a flange ring 11 is detachably secured, for instance with the help of screws 19, to the end face of the intermediate member 4a.

At the U-shaped portion of the retaining cam means 90 there engages the flange means 2a by means of its end flange portion 2b and which is coupled with the circular printing screen 1, so that the retaining cams 9a, on the one hand, serve .as support means and, on the other hand, as centering means.

These retaining cams 9a can be advantageously fixed at certain peripheral locations by means of a suitable adhesive agent.

Generally, however, it is sufficient to provide a locking arrangement or device, as such for instance is depicted in FIG. 5. As far as such locking arrangement is concerned, it will be seen thatsuch incorporates a bolt member 21 which is loaded by a spring 20 and which engages in a notch 22 provided at the web portion 90 of the associated retaining or holding cam 9a and thus fixes the position of such holding cam.

As also best observed by referring to FIG. 4, it is possible to uniformly distribute about the periphery of the inventive mounting arrangement a number of, for instance three, retaining or holding cams 9a, so that the intermediate angle between each two neighboring holding cams amounts to F urthermore, if the peripheral extent, as indicated by reference character 12 in FIG. 4, of each holding or retaining cam 90 amounts to 30 for instance, then with a uniform distribution of the retaining cams 9a there results an angle 13 which amounts to 15. l-Ience, now if the holding or retaining cam, designated by reference character 9b in FIG. 4, is brought into the phantom line position appearing at the right-hand portion of the Figure, then the angle 14 likewise amounts to 15". By virtue of this arrangement of the retaining or holding cams 9a there results a segment of about where there are not situated any holdingcams. Consequently, the circular printing screen 1 can be radially removed and inserted in a most convenient fashion. In practice, the holding cam which, upon stopping of the rotary screen printing machine, is located toward the top, is advantageously always released and brought into bearing contact with a neighboring holding cam.

With the foregoing arrangement in mind, there will now be considered the manner in which a circular printing screen can be dismantled. During operation, the circular printing screen 1 is clamped between the intermediate members 4a. Upon stopping of the machine, it is necessary to initially remove the tension applied to the circular printing screen, which can be easily undertaken by appropriately axially displacing one of both support or bearing plates 8a. After the screen is situated in the retaining or holding cams 9a without any lengthwise tension, then that holding cam which is directed toward the top or located at the uppermost region, is removed from its locked position and displaced until it comes into contact with one of the neighboring retaining or holding cams. Thereafter, the circular printing screen 1 can be removed by lifting such essentially radially upwards. Even if one of the holding cams is not situated exactly at the highest point of the intermediate member 4a, still, it is possible to remove the circular printing screen in an approximately upward direction.

The insertion or remounting of the circular printing screen 1 takes place in the reverse sequence of steps. More precisely, such circular printing screen 1 is inserted and placed upon those retaining cams which'have not been displaced, whereby the screen is already centered. Now, the loosened and laterally shifted retaining or holding cam is again brought back into its original position and fixed thereat. Thereafter, the displaceable support or bearing plate 80 is axially displaced from the circular printing screen 1, so that the latter is again tensioned.

By virtue of the resiliently mounted arrangement of the intermediate members 4a it is possible, on the one hand, to regulate the lengthwise tension of the circular printing screen 1 and, on the other hand, to compensate for any inaccurate position of the flange means 2a at the circular printing screen.

The advantage of the described embodiment resides in the fact that in each arrested or stopped position of the circular printing screen the latter can always be removed essentially upwards or toward the top. The removal itself is exceptionally simple and can be undertaken after releasing the longitudinal or lengthwise tension of the circular printing screen and after displacing one of the retaining or holding cams. Furthermore, there is the additional advantage that the holding cams do not have to be pivoted outwardly, so that no difficulties can occur in the event that the machine is again placed into operation without the holding cams having been placed back into the correct position. The number of holding cams whichcan be used is not decisive, what is important is that the holding cams are displaceable in the peripheral direction so that sufficient space is provided for inserting and removing the circular printing screen.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset to the specification have been successfully achieved.

We claim: I

1. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen-to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular printing screen, biasing means for resiliently biasing said intermediate member, said biasing means including means for connecting said intermediate member to said support plate means, and means for connecting said intermediate member to said circular printing screen, so that said circular printing screen is secured to said support plate means via said intermediate member, said bias-- ing means including its connecting means incorporating a number of bolt means secured to said support plate means for centering said intermediate member, said intermediate member being provided with bore means, each of which receives one of said bolt means, pressure spring means carried by each of said bolt means, each of said bore means including a base portion, each of said bolt means including a bolthead, said pressure spring means bearing against the associated bolthead and the base portion of the associated bore means.

2. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular printing screen, biasing means operably connected with said intermediate member for resiliently biasing said intermediate member and'for tensioning said circular printing screen in the axial direction thereof, said biasing means including means for connecting said intermediate member to said support plate means, and means for termediate member, said circular printing screen' being rotatably secured to said support plate means via said intermediate member without any relative rotational movement existing between said circular printing screen and said support plate means, said means for detachably coupling said circular printing screen with said intermediate member comprising a number of retaining cams arranged at the periphery of said inten'nediate member for retaining and centering said circular printing screen, at least one of said retaining cams being displacea ly about the periphery of said intermediate member to permit radial insertion and removal of the circular printing screen.

3. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular, printing screen, biasing means for resiliently biasing said inte ediate member, said biasing means including means for connecting said intermediate member to said support plate means, and means for coupling said intermediate member to said circular printing screen, so that said circular printing screen is secured to said support plate means via said intermediate member, said coupling means further including a number of retaining cams arranged at the periphery of said intermediate member for retaining and centering said circular printing screen, at least one of said retaining cams being displaceable about the periphery of said intermediate member to permit radial insertion and removal of the circular printing screen.

4. A rotary screen printing machine as defined in claim 3, wherein at least three retaining cams are uniformly arranged about the periphery of said intermediate member, whereby upon displacement of the uppermost located retaining cam until it comes into contact with a neighboring retaining cam there is provided a cam-free segment extending through at least about the periphery of said intermediate member, so that the circular printing screen can be approximately vertically inserted from above through said cam-free segment.

5. A'rotary screen printing machine as defined in claim 3, further including groove means provided at the periphery of said intermediate member, said retaining cams being displaceably mounted in said groove means.

6. A rotary screen printing machine as defined in claim 3, wherein each of said retaining cams extends about the periphery of said intermediate member through an angle of at most 30.

7. A rotary screen printing machine as defined in claim 3, further including groove means provided at the periphery of said intermediate member, and means for releasably locking said retaining cams at predetermined locations of said peripheral groove means.

8. A rotary screen printing machine as defined in claim 7, wherein said releasable locking means comprise spring loaded bolt means associated with said retaining cams for engaging with a notch provided at the associated retaining cam. 

1. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular printing screen, biasing means for resiliently biasing said intermediate member, said biasing means including means for connecting said intermediate member to said support plate means, and means for connecting said intermediate member to said circular printing screen, so that said circular printing screen is secured to said support plate means via said intermediate member, said biasing means including its connecting means incorporating a number of bolt means secured to said support plate means for centering said intermediate member, said intermediate member being provided with bore means, each of which receives one of said bolt means, pressure spring means carried by each of said bolt means, each of said bore means including a base portion, each of said bolt means including a bolthead, said pressure spring means bearing against the associated bolthead and the base portion of the associated bore means.
 2. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular printing screen, biasing means operably connected with said intermediate member for resiliently biasing said intermediate member and for tensioning said circular printing screen in the axial direction thereof, said biasing means including means for connecting said intermediate member to said support plate means, and means for detachably coupling said circular printing screen with said intermediate member, said circular printing screen being rotatably secured to said support plate means via said intermediate member without any relative rotational movement existing between said circular printing screen and said support plate means, said means for detachably coupling said circular printing screen with said intermediate member comprising a number of retaining cams arranged at the periphery of said intermediate member for retaining and centering said circular printing screen, at least one of said retaining cams being displaceably about the periphery of said intermediate member to permit radial insertion and removal of the circular printing screen.
 3. A rotary screen printing machine having a machine frame and comprising a substantially circular printing screen for each printing station thereof, means for mounting each circular printing screen to said machine frame so that, depending upon the requirements, it can be removed and again reinserted, said mounting means for said circular printing screen comprising support plate means rotatably disposed at the machine frame, an intermediate member located between said support plate means and said circular printing screen, biasing means for resiliently biasing said intermediate member, said biasing means including means for connecting said intermediate member to said support plate means, and means for coupling said intermediate member to said circular printing screen, so that said circular printing screen is secured to said support plate means via said intermediate member, said coupling means further including a number of retaining cams arranged at the periphery of said intermediate member for retaining and centering said circular printing screen, at least one of said retaining cams being displaceable about the periphery of said intermediate member to permit radial insertion and removal of the circular printing screen.
 4. A rotary screen printing machine as defined in claim 3, wherein at least three retaining cams are uniformly arranged about the periphery of said intermediate member, whereby upon displacement of the uppermost located retaining cam until it comes into contact with a neighboring retaining cam there is provided a cam-free segment extending through at least 180* about the periphery of said intermediate member, so that the circular printing screen can be approximately vertically inserted from above through said cam-free segment.
 5. A rotary screen printing machine as defined in claim 3, further including groove means provided at the periphery of said intermediate member, said retaining cams being displaceably mounted in said groove means.
 6. A rotary screen printing machine as defined in claim 3, wherein each of said retaining cams extends about the periphery of said intermediate member through an angle of at most 30*.
 7. A rotary screen printing machine as defined in claim 3, further including groove means provided at the periphery of said intermediate member, and means for releasably locking said retaining cams at predetermined locations of said peripheral groove means.
 8. A rotary screen printing machine as defined in claim 7, wherein said releasable locking means comprise spring loaded bolt means associated with said retaining cams for engaging with a notch provided at the associated retaining cam. 